Recently, various types of personal computers (PCs) have been widespread. As for business use in companies, for example, portable type PCs which can be easily carried into meetings etc., have been frequently used.
When users use such PCs for business, the users usually have needs for connecting the PCs both to the Internet and an office network, and so various security measures responding to the needs have been developed. In general, to completely eliminate a risk of information leak from the companies to the Internet and the like, an operating environment of PCs for connecting to the Internet and to the office network is desirably separated from each other. However, it will be uneconomical and inconvenient for each of the user to use two PCs, each respectively connecting to the Internet and the office network.